Diffractive optical waveguide and display device

Abstract

The present application provides a diffractive optical waveguide for optical pupil expansion and a display device. The diffractive optical waveguide comprises a waveguide substrate having a coupling-in region and a coupling-out region that includes a first coupling-out region, a second coupling-out region, and a transitional region; a coupling-in grating; and a coupling-out grating. The coupling-out grating comprises first and second coupling-out gratings and a plurality of transitional coupling-out grating. The first and second coupling-out gratings are arranged in a first direction. The transitional region comprises a plurality of sub-regions each correspondingly provided with one of transitional coupling-out gratings. The transitional coupling-out grating has a first, a second, and a third vector direction. The third vector direction is parallel to the vector direction of the first coupling-out grating. The first vector direction forms a first included angle with the third vector direction, and the second vector direction forms a second included angle with the third vector direction. The first included angle corresponding to the one, in two neighboring transitional coupling-out gratings, closer to the second coupling-out grating is greater than the first included angle corresponding to the farther one; and/or, the second included angle corresponding to the one closer to the second coupling-out grating is greater than the second included angle corresponding to the farther one.